Leaf Mould

Made a start on plot 5 today. Down at the bottom where it tends to get waterlogged in wet weather, I’ve some raised beds. Now although I’m not a huge fan of raised beds, the fact is that when your plot is a bit out of control, you can attack a bed at a time and feel you’re winning.

One bed is devoted to asparagus and this is a difficult crop to weed. It’s got shallow spread roots and hoeing the roots or worse still, the crown, is not the best way to grow it!

The soil in the bed wasn’t the best quality and seems to have reverted to being clayish so it was a little difficult to hoe, especially as weeding next to the crowns is a hand job.

Once cleared and the soil surface broken up, I gave it some fish, blood & bone to help it with spear production and then mulched with an inch of leafmould. Leafmould is one thing that is really under rated in the gardening world and I’ve heard some nonsense about making it.

Unlike compost which benefits from heat and being turned to promote microbial action etc, all leafmould requires is time, a little moisture and air. Leaves in the wood fall to the ground and gradually decompose without any additions.

Adding compost activator or extra nitrogen will not speed up the decomposition of leaves into leaf mould. The only thing you can do to speed up the process is to break the leaves into smaller pieces. Those leaf vacuums that mulch them at the same time are great for this.

We get our leaves dropped off in huge piles by the council, so that’s not really an option. I pile them up in a wire sided cage and forget them for a year at least. Actually, if you can, two or even three years is better.

Leafmould has no nutritional value. If you think about it, the tree sucks all the goodness back out of the leaf, which makes it turn to those gorgeous autumn colours, before allowing them to fall to the ground.

What leafmould does have is a fabulous structure, very much like peat. So it makes a great soil conditioner, opening clay soils and binding sandy soils. It holds moisture but allows drainage and makes it a lot easier to work heavy soil.

The texture is ideal for making your own potting compost as well, just like peat but a very renewable resource. As I said, leafmould has no nutritional value but you can add it in. One good trick is to layer lots wilted comfrey in layers as you build up your leaf mould pile.

If you do that, the comfrey adds a lot of nutrients but not too much nitrogen and after a year or two you have a great seed compost. Because the rain will wash out the nutrients, cover the bin with some plastic sheet or suchlike but do ensure the pile remains damp.

You can make leaf mould on a smaller scale – just put the leaves into black plastic sacks, poke some airholes in the sacks and add some water if dry. Stick the sacks somewhere, perhaps the shaded place behind the shed where nothing grows anyway, and leave for a year.

Do be aware that the leaves shrink down an awful lot – my five foot high pile of densely packed leaves ended up a foot high.

Posted in Allotment Garden Diary
12 comments on “Leaf Mould
  1. caroline says:

    With my cheap nasty vacuum from aldi I can take the bag off the back and it blows the shredded leaves out the back with the vacuum on “suck”.So you could suck up all the intact council leaves and blow them out as shredded ones into a eg a dumpy bag. It means that the leaves that go hard and shiny dont seem to be left in amongst the mould when its almost done.

  2. Jeff says:

    The local school near me has piled up all of their leaves. Unfortunately the leaves have basically smouldered down to about 75 percent ash. There is a huge amount of them though and I was wondering if this material would still be suitable to use as mulch or soil conditioner. Any idea? Thanks for the blog btw, very informative.

  3. John says:

    Jeff – difficult to say without looking but I’m sure they’d do no harm and would probably do a lot of good.

  4. Jeff says:

    Thanks John, I have piled up about 2 inches on one of my new beds (about 2 months ago) and have just forked it over. Considering the bed was big chunks of heavy clay, the smouldering leaf mulch has really worked wonders on it. I now have a reasonably good new bed for planting in this year. Not a moment too soon as I was running out of space! Good luck and keep up the blog.

  5. Su says:

    I have a number of bags of leaves moldering away on my allotment, as I am keen to have as much leafmold as poss. It has been there 1 yr so far. Ilike the idea of adding comfrey. Could I do this now,water the leaves and re-bag?
    By the way, have been reading yr diaries and buying yr books for a while, many thanks for all the help! Su

  6. John says:

    I don’t see why not – comfrey rots down really quickly.

  7. TW says:

    “Leafmould has no nutritional value. If you think about it, the tree sucks all the goodness back out of the leaf, which makes it turn to those gorgeous autumn colours, before allowing them to fall to the ground.”

    I’m not convinced by this: here’s why.

    When I was small my gandparents employed an old school gardener (he lied about his age to join up in 1914 and held horses on the Somme. After that he came home for a quite life and became a gardener). He used to make leaf mold by piling up autumn leaves outside and it was always full of the most enormous earthworm I used to catch to use as bait for fishing. Those worms must have eaten something and their wormcasts must have been great for the soil.

    Old Mr Simmons used to make his own compost, including the rotted leaf mold. I can see him sieving it now.

  8. JJ says:

    I’m a huge believer in leaf mould – there are just so many ways to use it.

    1. Bag/bin it and wait a couple of years for great soil conditioner (seeds or cuttings)
    2. Use as a winter cover for beds, then dig it in when spring comes around – it will have protected and kept the bed warm – dig it in and it will provide some structure too.
    3. Mulch around fruit bushes – perfect for covering the soil around fruit bushes all year round
    4. The birds love it! It’s perfect for them to search out grubs/bugs

    The trick is to think of how nature works and copy it!

    Great blog – thanks.

  9. Lizzie says:

    Can anyone tell me what the fine mat of browny orange roots are that grow through my leaf mould heap.

    • Linda says:

      I was only wondering the sane thing? Thought it might be the leaf trying to reproduce itself. I know you can propagate from some leaves but that’s generally when they are green ‍♀️

    • John Harrison says:

      Lizzie, sounds like mycelium from a fungus running through the leafmould. Don’t worry, it’s harmless and is part of the way fallen leaves decompose.

  10. David Etherton says:

    I have found Nutscene jute leaf composting sacks, 95cm x 65cm. Pack of two £4.50 which seemed reasonable. So giving them a try this year with leaves from the garden, has anyone had experience of using these?

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